1. Field of the Invention
The present invention relates generally to vehicle rear impact guards, and in particular to rear impact guards used with lifts and dock locks.
2. Description of Related Art
Rear impact guards, or commonly known as underrides, are used to reduce the chance of following vehicles from driving underneath the bed of a vehicle such as a truck or a trailer. FIG. 1A shows a rear view of a vehicle 10, such as a conventional truck or trailer, with a fixed horizontal underride 12 (relative to ground level 28), installed below the vehicle bed 14 via vertical beams 17. As shown in the side view of the vehicle 10 in FIG. 1B, the underride 12 is positioned under the end of the vehicle close to or flush with a plane 11 of the rear end of the vehicle 10. The vertical height S1 between the underride 12 and the ground level 28 is at a predefined distance (e.g., no more than 22 inches) suitable to reduce the chance of following vehicles from traveling underneath the bed of a vehicle. The distance S2 from an edge of the underride 12 to the side end of the vehicle 10 is also at a predefined range (e.g., no more than 3.9 inches).
Such fixed underrides 12 are also often used with dock locks (truck locks) 102 to prevent the vehicle from being pushed away or “seesawing” while the vehicle is parked at a dock 40 or other loading facility (FIGS. 1B-1C). A dock lock 102 may include a bar, hook, and/or platform, which engages, holds, latches, and/or supports the underride. A typical dock lock 102 is designed to operate with such underrides 12, wherein the dock lock 102 is fixedly positioned by a plate 13 within a short grabbing distance N from the dock 40. During loading and unloading operations, the vehicle 10 is backed up to the dock 40 against slight bumpers 23, wherein the vehicle bed 14 is generally horizontally aligned with the upper surface of the dock (FIG. 1B). A dock lock 102 engages or grabs a center portion of the underride 12, thus locking the vehicle 10 in position relative to the dock 40 (FIGS. 1B-1C).
Further, lifts such as liftgates are typically mounted at a structure such as the rear of a vehicle to lift payloads on a platform from one level (e.g., ground level) up to another level (e.g., the bed of the vehicle), or vice versa. A common type of lift, known as a stow lift (tuck under lift), includes a platform that is tucked (stowed) under the vehicle bed when not in use, and can be untucked (unstowed) when needed. In this type of lift, the platform is typically foldable and is linked to an actuator which can raise and lower the platform, as well as stow and unstow the platform. The conventional underride 12 shown in FIG. 1 is fixed to the vehicle 10 so that the underride 12 cannot move. As a result, such an underride 12 is not compatible with a lift that is stowed under the rear end of the vehicle since the underride 12 interferes with the stowing and unstowing of the lift.